wolfgram



1959 R. c. WOLFGRAM 2,877,836

CONTROL APPARATUS FOR BURNERS Filed May 1, 1957 2 Shets ;-Sheet 1 INVENTOR. RODGER C. OLFGRAM iM A ATTORNEY R. C. WOLFGRAM CONTROL APPARATUS FOR BURNERS March 17, 1959 2 Sheets-Sheet 2 I Filed May 1, 1957 N v D W S O P N m SAFETY LOCKOUT POSITION IN VENTOR. RODGER C. WOLFGRAM ATTORNEY CONTROL APPARATUS FOR BURNERS Rodger C. Wolfgram, Bloomington, Minn., assignor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Application May 1, 1957, Serial No. 656,325

Claims. (Cl. 158-28) The present invention is concerned with an improved control apparatus and more specifically with an improved burner control apparatus. I

The present invention is an improvement over the copending application of John F. Werr and Rodger C. Wolfgram, Serial No. 652,568, filed April 12, 1957. More specifically, the present invention utilizes a combustion responsive means and timer assembly which are so inter-related to provide the optimum in safe operation of a burner unit with a minimum of cost. The present invention utilizes a single bimetal timer to obtain both ignition timing and safety switch timing, the operation of the bimetal timer being supervised by the combustion responsive means which functions to reset the bimetal timer to the start condition upon a flame being detected and the absence of flame being subsequently detected. The present invention provides an improvement over the above mentioned co-pending application in that an improved and simplified arrangement eliminates the need for certain components, thereby simplifying the burner control and reducing its cost.

It is therefore an object of the present invention to provide an improved burner control apparatus which is adapted to be mounted on the stack of a fuel burner unit and which utilizes a timing arrangement to provide both a starting interlock contact and safety switch timing and utilizing an improved and simplified electrical circuit to produce optimum safe operation of the fuel burner unit.

Other objects of the present invention will be apparent to those skilled in the art upon reference to the following specification, claims, and drawings, of which Figure 1 is a schematic representation of the present invention showing a combustion responsive means and a timer and the manner in which these two elements are inter-related;

Figure 2 is a view partly in section of a portion of the apparatus of Figure 1;

Figure 3 is a showing of the combustion responsive means and timer of the apparatus of Figure 1 in the run position; and

Figure 4 is a showing of the combustion responsive means and timer of the apparatus of Figure 1 in the safety lockout position.

Referring specifically to Figure 1, the reference numeral designates a fuel burner unit having a motor 11 and ignition transformer 12. The ignition transformer 12 is connected by means of electrical conductors to produce a spark at ignition electrodes 13 and thereby ignite the oil emitting from the nozzle of the fuel burner unit 10. The improved burner control for the fuel burner unit 10 is shown within the broken lines designated by the reference, numeral 14.

This improved burner control includes a transformer relay 15 having a primary winding 16, a tapped second ary Winding 17, and a movable armature 18 which controls switches 19 and 20. The switches 19 and 20 are States Patent 0 upon energization of the secondary winding 17. ,In other words, upon an electrical circuit being completed so that current may flow through the secondary winding 19, the armature 18 moves in a downward direction to close switches 19 and 20. The means for moving armature 18 is represented by the broken line 21.

The reference numeral 22 designates a combustion responsive means having a combustion responsive bimetal 23 which is adapted to be located relative to the fuel burner unit 10 to be heated when a flame is present at the fuel burner. For example, this may be a stack mounted burner control wherein the combustion responsive bimetal 23 extends into the stack so that the products of combustion from the furnace pass over and heat the bimetal 23.

Bimetal 23 is connected to a wheel 24 having a pivot 25 and a knob portion 26. The wheel 24 is provided about its outer circumference by a series of serrations or notches, as shown in Figure 1. The mechanical co operation between wheel 24 and bimetal 23 is represented by the broken line 27 and this mechanical cooperation is such that wheel 24 rotates in a clockwise direction upon the combustion responsive bimetal 23 being subjected to a temperature rise. This has been indicated in Figure 1 by means of an arrow. Upon a subsequent temperature drop, as evidenced by the absence of flame at the fuel burner unit 10, the wheel 24 totates in a counter-clockwise direction.

The rotation of wheel 24 controls the position of a spring biased rod 28 which is mounted within a pivoted yoke member 29, pivoted at pivot 30. Thespring biased rod 28 passes through an opening in the upper portion 31 of the yoke 29 and likewise through an opening 32 in a lower portion of this member. A fastening member 33 is provided which is fixed to the rod 28 and serves as the upper bearing surface for a spring 34. The lower surface of the spring 34 bears against the surface sur rounding opening 32 and thereby spring biases rod 28 in an upward direction.

The upper portion of the spring biased rod 28 includes a knife like member 35 which engages the notches or serrations on the circumference of wheel 24. In this manner, as wheel 24 rotates, the rod 28 and its yoke 29 follow the rotation of wheel 24, moving from one side to the other of the center of rotation 25.

Movement of the spring biased rod 28 causes movement of combustion responsive switch means designated generally by the reference numeral 36. This switch means 36 includes a spring blade 37 which is coupled to a member 38. This member 38 in turn is controlled by and coupled to the spring bias rod 28.

The combustion responsive switch means 36 includes a first switch 39 and a second switch 40. The switch 39 is closed in the absence of flame at the fuel burner unit 10 while the switch 40 is closed in the presence of flame at the burner unit.

The yoke member 29 which is controlled by and mounts the spring biased rod 28 also includes an extended portion 41 on which a flexible spring 42 is mounted. As will be described, the spring 42 co-operates with a latch member 43.

The reference numeral 44 designates generally a timing means in the form of a bimetal timer having a compensating bimetal 45 and an active bimetal 46. A heater 47 is associated with the active bimetal 46 and is adapted to heat this bimetal upon heater 47 being energized. As

. has been shown by means of an arrow in Figure 1, the

normally open switches and are adapted to be closed lower end of bimetal 46 moves to the right upon being heated by heater 47. v

The lower end of bimetal 46 engages a knee portion 48 of the latch member 43. This latch member 43 is pivoted at pivot 49 and is biased for rotation in a counter- 3 clockwise directionbymeans of a spring 50. However, the rotation of latch 43 in thecounter-clockwise direction is restricted by the bimetal 46 of timer 44.

The latch member 43. includes aswitch operating extension 51 which co-operates with a pair of switch blades 52 and 53 to control the position of these switch blades. Switch blade 52 co-operates with a contact 54 whereas switch blade 53 co-operates with a contact 55.

Further, as shown inFigure l, the spring member 42 which is operated by movement of the rod 28 passes through an opening 56 inthe latch member 43. This can be seen in Figure 2 wherein portions of the latch member 43, the bimetal 46, the extension 48 and the spring blade 42 have been shown in section. From this view it can be seen that with the timer in the cold position, shown in Figure 1, the spring element 42 extends through the opening 56 in the latch member 43 and in no way restricts movement of this latch member.

The operation of the combustion responsive means 22 and the timer 44 and the manner in which the latch means 43 is controlled jointly by these two structures will now be explained. The apparatus of Figure 1 is shown in its standby condition wherein the combustion responsive means 22 is detecting the absence of flame at the burner unit and the timer 44 is in its initial or cold position. Upon energization of heater 47, bimetal 46 moves to the right to release the latch member 43, as shown in Figures 3 and 4. In this condition, the extension 51 of latch member 43 causes switches 5254 and 53-55 to assume their open conditions. Furthermore, in the event that bimetal 46 subsequently cools, the bimetal cannot return to its original or cold position due to the fact that its movement is restricted by the latch member 43, as shown in Figures 3 and 4.

The showing of the bimetal. timer 44 and the latch member 43 is identical in Figures 3 and 4. However, in Figure 3 the combustion responsive means 22 is shown in the condition detecting the presence of flame at the burner unit 10 while in Figure 4 the combustion responsive means 22 is detecting the absence of flame at the burner unit 10. In the absence of flame at the burner unit, the combustion responsive switch means 36 is maintained in its initial condition, that is with switch 39 closed and switch 40 open, as shown in Figures 1 and 4. Furthermore, the spring means 42, which is controlled by movement of spring biased rod 28, continues to extend through the opening 56 in the latch member 43, it being remembered that latch member 43 has rotated counterclockwise under the bias of spring 50.

However, in the event that combustion responsive means 22 responds to the presence of flame at the burner unit 18, the springbiased rod 28 moves in a counterclockwise direction about pivot from the position shown in Figures 1 and 4 to the position shown in Figure 3. In this position, the spring member 42 is withdrawn from the opening 56 provided in latch member 43 and the combustion responsive switch means 36 is actuated to the condition indicative of the presence of flame at the burner unit 10. That is, switch is closed and switch 39 is open.

As will be described more completely, the showing of the apparatus of Figure 3 is the run position of this portion of the control apparatus 14, whereas the showing of the apparatus in Figure 4 is the safety lockout position. In either position, it is necessary for latch member 43 to be rotated clockwise to release bimetal 46 so that it may once again assume its cold position as shown in Figure 1. In Figure 3 this rotation is achieved by the combustion responsive means 22 detecting the absence of flameat the burner. unit 10 to cause wheel 24 to rotate in .a counter-clockwise direction. biased rod 28 to rotate in a clockwise direction about pivot 30 and as this. rotation continues the spring member142 bears against the-upper surface of the latch member. 43 in. the vicinity, of; theopening 56.. This causes.

This causes the spring.

the latch member 43 to rotate in a clockwise direction about pivot 49 until the bimetal 46 is released to assume its cold position as shown in Figure 1 and until the spring member 42 snaps through the opening 56 in the latch member, thereby placing the apparatus in the condition shown in Figure 1.

Spring member 42 is formed of a resilient material and as rod 28 rotates about pivot 36, this member 42 first engages latch member 43 and then causes this member 43 to rotate about pivot 49, against an increasing force exerted by spring 50. As rod 28 and latch member 43 rotate, spring member 42 is deformed, the lower end being bowed concave upward to the right. Shortly after latch member 43 has rotated a sutficient distance to cause bimetal 46 to assume its cold position, the force exerted by spring 50 causes suflicient bowing of member 42 to cause this member to snap through the opening 56.

In the event that the apparatus is in the safety lockout position as shown in Figure 4, it is necessary to cause manual rotation of the wheel 24 by manually rotating knob 26 in a clockwise direction against the bias force set up in bimetal 23, thereby simulating the presence of flame at the burner unit 10 to cause the spring biased rod 28 to assume the position shown in Figure 3. The knob 26 is then released and due to the bias built up in bimetal 23 as it was manually rotated, the wheel 24 rotates in a counter-clockwise direction in the same manner that the wheel was rotated as a result of a temperature fall at the bimetal 23. This causes the spring biased rod 28 to rotate in a clockwise direction about its pivot and this in turn causes spring member 42 to engage and reset the latch member 43, as above described.

The overall operation of the improved burner control apparatus will now be described. The apparatus is shown.

in Figure 1 in its standby condition. That is, there is no call for operation of the burner unit 10. Such a need for operation of the burner unit is indicated by a thermostat 56 which is connected to terminals of the burner unit 14. Upon there being a need for operation of the burner unit 10, thermostat 56 closes its switch to complete an initial energizing circuit for the secondary winding 17 of transformer relay 15. This initial energizing circuit can be traced from the right hand terminal of secondary winding 17 through conductor 57, thermostat 56, conductors 58 and 59, combustion responsive switch 39, conductors 60 and 61, start switch 53--55, conductor 62, heater 47, and conductor 63 to the left hand terminal of secondary winding 17. From this above traced circuit it can be seen that the initial energizing circuit for the secondary winding of the transformer relay 15 cannot be completed unless the timer 44 is in its cold position wherein the latch member 43 maintains the start switch 53-55 closed. Furthermore, there must be electrical continuity-in the heater 47 and the combustion responsive means 22 must be in the condition indicating the absence of flame at the burner unit 10, as evidenced by switch 39 being in its closed condition.

Energization of the secondary winding of transformer relay 15 causes armature 18 to move in a downward direction thereby closing switches 19 and 20. The closing of switch 2i) completes a circuit which shunts combustion responsive switch 39. This circuit can be seen by tracing a circuit from spring blade 37 through conductors 60 and 64, switch 20, and conductors 65 and 59 to the other side of switch 39.

The closing of switch 19 completes an energizing circuit for both the motor 11 and the ignition transformer 12 of the fuel burner unit 10. The energizing circuit for motor 11 can be traced from power line conductors 66 and 67, which are connected to a source of alternating voltage not shown, as follows: conductors 66 and 68, switch 19, conductors 69 and 76, motor 11, and con: ductors 71 and 72 to power line conductor 67. The energizing circuit for the ignition transformer 12 can be traced from power line conductor 66 through conductor 68, switch 19, conductors 69 and 73, switch 54-52, conductor 74, ignition transformer 12, and conductors 75 and 72 to power line conductor 67. The last two traced circuits cause a flame to be established at the burner unit 10. This in turn causes the combustion responsive bimetal 23 to experience a temperature rise.

Therefore, both the bimetal 23 and the bimetal 46 experience a temperature rise, the former being due to the presence of flame at the burner unit and the latter being due to energization of the heater 47. The timing function provided in timer 44, that is the time necessary for bimetal 46 to move from its cold to its hot position, provides the safety period during which flame must be established at the burner unit 10. Normally, flame is established in this time period and the combustion responsive means 22 functions as above described to move the wheel 24, the spring biased rod 28, and the spring means 42 to the position shown in Figure 3. This opens combustion responsive switch 39 and closes combustion responsive switch 40. The closing of combustion responsive switch 40 completes a running energizing circuit through a first portion of the secondary winding 17 of transformer relay 15. This circuit can be traced from the right hand terminal of the secondary winding 17 through conductor '57, thermostat 56, conductors 58 and 65, switch 20, conductors 64 and 60, combustion switch 40, and conductor 77 to a tap 78 of secondary winding 17. It can be seen that this running energizing circuit exists so long as there is a need for operation of the burner unit 10 as evidenced by thermostat 56 remaining in its closed condition and so long as combustion responsive means 22 senses the continued presence of flame at the burner unit 10.

It will be noted from the above traced circuit that the heater 47 of timer 44 is not in the running energizing circuit of the transformer relay 15. However, it is necessary to maintain heater 47 energized to cause bimetal 46 to move to its hot position to thereby deenergize the ignition transformer 12 and to open the start contact 53-55 located in the initial energizing circuit of the transformer relay. This maintaining energizing circuit for heater 47 can be traced from the tap 78 through conductor 77, switch 40, conductors 60 and 61, starting switch 55-53, conductor 62, heater 47, and conductor 63 to the left hand terminal of secondary winding 17. From this circuit it can be seen that once flame is detected by the combustion responsive means 22 to thereby open switch 39 and close switch 40, the transformer relay 15 is maintained energized through a first portion of its secondary winding whereas the heater 47 of timer 44 is maintained energized through a second portion of its secondary winding.

After a predetermined time period of energization of heater 47, bimetal 46 moves to the right and the apparatus assumes the position shown in Figure 3, switch 52-54 opening to thereby open the start circuit of the apparatus.

The opening of the start switch 53-55 also deenergizes the heater 47 of timer 44 and thereby causes the bimetal 46 to cool. However, this bimetal may not assume its cold position since it is retained in its hot position by latch 43 as shown in Figure 3.

The apparatus continues to operate as shown in Figure 3 until there is no longer a need for operation of the burner unit 10, as evidenced by thermostat 56 opening its switch. The opening of the thermostat switch causes the transformer relay 15 to' be de-energized and the switches 19 and 20 thereby assume their open condition. The opening of switch 19 de-energizes the burner motor 11 and the flame at the burner unit 10 is extinguished. The combustion responsive bimetal 23 there- 'fore experiences a temperature drop and the wheel 24 rotates in a counterclockwise direction. This causes the spring member 42 to engage the upper-surface of the latch member 43 in the vicinity of the opening 56 and,

as above described, this in turn causes latch member 43 to be rotated in a clockwise direction about its pivot 49 to allow the elements of the improved burner control apparatus to once again assume the condition shown in Figure 1.

In the event that the thermostat 56 only momentarily opened its switch, the fuel burner unit 10 cannot again be energized until the combustion responsive bimetal 23 has cooled to reset the apparatus to the condition shown in Figure 1. This provides a purging period during which the combustion gases leave the furnace and thereby prevents an immediate recycle with a possible explosion due to raw fuel in the fire box surrounding the burner unit 10.

Assume now that there is a further call for operation of the burner unit 10 as evidenced by thermostat 56 closing its switch. As above described, the burner unit 10 including motor 11 and ignition transformer 12 are energized. Assume further that due to a malfunction of one sort or another a flame is not established. at the burnerunit 10. The combustion responsive means 22 .therefore remains in the condition shown in Figures 1 and 4. However, the heater 47 of timer 44 remains energized through the initial energizing circuit, above traced, for the secondary winding 17 of transformer relay 15. After a predetermined time period of energization of heater 47 the bimetal 46 warps to the right and the latch member 43 rotates in a counterclockwise direction about its pivot 49 to assume the position shown in Figure 4. This opens the start switch 53-55 and therefore de-energizes the secondary winding 17 of transformer relay 15. Furthermore, the opening of start switch 53-55 deenergizes the heater 47 which is in the initial energizing circuit of transformer relay 15. Bimetal 46 then cools but is latched in its hot position by latch member 43 as shown in Figure 4. It is now necessary for the Wheel 24 to be manually rotated in a clockwise direction, thus simulating a temperature rise at bimetal 23. As above described, the rotation of wheel 24 and the subsequent rclease of this wheel so that it may rotate in a counterclock wise direction under the bias built up in bimetal 23 causes the latch member 43 to be reset to the condition shown in Figure 1, thereby again placing the apparatus 14 in the standby condition.

From the above description it can be seen that I have provided an improved burner control apparatus and it is intended that the scope of the present invention be limited solely to the scope of the appended claims.

I claim as my invention:

1. Burner control apparatus for use with a fuel burner unit having ignition means comprising: a transformer relay having a tapped secondary winding and having a movable armature controlling a first and second switch, said first and second switch being movable from circuit opening to circuit closing condition upon a circuit being completed through said secondary winding; combustion responsive means including a bimetal element arranged to be subjected to the presence or absence of flame at the fuel burner unit, a movable member controlled by said bimetal element and arranged to move from a first to a second position upon said bimetal element experiencing a temperature rise due to the establishment of flame at the fuel burner unit, said movable member moving from said second to said first position upon said bimetal element experiencing a subsequent temperature fall due to absence of flame at the fuel burner unit, a first and a second combustion responsive means switch controlled by said movable member; a bimetal timer having an active bimetal and a heater associated therewith, a latch member biased to move in a first direction and associated with said timer bimetal such that said bimetal timer restricts the move ment of said latch member when said bimetal timer is in said cold position, said bimetal timer moving to a hot position after a time period of energization of said timer heater to thereby release said latch member and allow said latch member to move in said first direction, a

'starting switch and an ignition switch: controlled by said latch member and arranged to be in circuit closing condition when said latch member has its movement restricted ,by'said bimetal timer, said start switch and ignition switch moving to open circuit condition upon said bimetal timer moving to said hot position; means controlled by said means switch, said timer start switch, and said bimetal timer heater connected in a series circuit to the end terminals of said secondary winding, energizing circuit means for said burner unit including terminals adapted to be connected to the fuel burner unit, said energizing circuit means arranged to control the motor of the fuel burner unit under the control of a first switch of said relay and the ignition means being controlled by said first relay switch and said timer ignition switch, and running circuit means for said transformer relay secondary winding including said second combustion responsive means switch and the second switch controlled by said relay connected in a series circuit to one end terminal and the tap of said secondary winding and connecting said bimetal timer heater and said start switch in a series circuit to the other end terminal and the tap of said secondary winding.

2. Burner control apparatus for use with a fuel burner unit having a thermostat responsive to the need for operation of the fuel burner unit and having a motor and ignition means, comprising: a transformer relay having a secondary winding provided with an intermediate tap and two end terminals, an armature for said transformer relay arranged to control a first and second switch to move said first and second switches to circuit closing condition upon a circuit being completed through the secondary winding of said transformer relay; combustion responsive means including a bimetal element arranged to be heated by the presence of flame at the fuel burner unit and including a wheel member arranged to be rotated in a first direction upon said bimetal element experiencing a temperature rise and to be rotated in a second direction upon said bimetal element experiencing a temperature fall, a movable member engaging the circumference of said wheel and arranged to move from a first to a second position in response to said wheel rotating in said first direction, said movable member moving from said second to said first position upon said wheel subsequently experiencing rotation in said second direction; a bimetal timer having a bimetal operator and an electrically energizable heater associated therewith, said bimetal operator moving from a cold to a hot position after a time period of energization of said timer heater, a latch member biased for movement from a first to a second position and engageable by said bimetal operator in said cold position to hold said latch member in said first position, a start switch and an ignition switch controlled by said latch member and arranged to be in circuit closing condition when said latch member is in said first position, means controlled by said combustion responsive means movable member and co-operating with said latch member to reset said latch member from its second to its first position upon said movable member moving from said second to said first position; a first and second combustion responsive means switch, controlled by said combustion responsive means movable member to cause a first of said switches to move from closed to open circuit condition upon said combustion responsive means movable member moving from said first to said second position and to cause the second of said combustion responsive means switches to move from open circuit to closed circuit condition upon said combustion responsive means movable member moving from said first to said second condition; initial energizing circuit means connected to the end terminals'of said secondary winding and including terminals adapted to be connected to the thermostat, said initial energizing circuit including said timer heater, said start switch, and said first combustion responsive means switch in a series circuit; energizing circuit means for the burner motor controlled by said first transformer relay switch, energizing circuit means for the ignition means controlled by said first transformer relay switch and said ignition switch; an intermediate energizing circuit for said secondary winding including said second transformer relay switch connected in parallel with said first combustion responsive means switch; and a running energizing circuit for said secondary winding including said second combustion responsive means switch connected to said secondary winding intermediate tap to thereby maintain a circuit through a first portion of said secondary winding under the control of said second combustion means switch and said second transformer relay switch, said second combustion responsive means switch further temporarily maintaining said timer heater energized from a second portion of said transformer relay secondary windingin a series circuit which includes said bimetal heater, said start switch,'and said second combustion responsive means switch.

3. Burner control apparatus for use with a fuel burner having means responsive to the need for operation of the fuel burner, comprising: relay means having an actuator and a switch operated thereby from a normally open to a closed condition upon energization of said actuator, a source of voltage having a first and a second portion, flame responsive means arranged to be positioned to respond to the presence or absence of flame at the fuel burner and having a member movable from a first to a second position upon said flame detector detecting the presence of flame, said movable member moving from said second back to said first position upon said flame responsive means sensing the subsequent absence of flame at the fuel burner, a switch controlled by said flame responsive means and movable from an open to a closed condition by said movable member as said movable member moves from said first to said second position, timer means having an electrical energizable actuator, a starting switch movable from a closed to an open circuit condition, a movable latch member co-operably associating said timer means and said flame responsive means movable member with said starting switch, said latch member being arranged to initially latch said starting switch in said closed condition and after a time period of energization of said timer actuator to latch said starting switch in said open circuit condition, said flame responsive means movable member being effective upon movement from said second to said first position to reset said latch member and thereby reset said starting switch to the condition wherein said starting switch is again closed, initial energizing circuit means for said relay means actuator and said timer actuator including said first and second portions of said source of voltage and including terminals adapted to be connected to the means responsive to the need for operation of the fuel burner and including said starting switch and said timer actuator, whereby after a predetermined time period of energization of said timer actuator said starting switch opens and causes deenergization of said timer actuator, running circuit means including the switch of said flame responsive means arranged to maintain said relay means actuator energized by means of said first portion of said voltage source and to maintain said timer actuator temporarily energized through said start switch by means of said second portion of said voltage source, and fuel burner energizing circuit means including terminals adapted to be connected to the fuel burner and including the switch of said relay means.

4. A burner control apparatus for use with a fuel burner having ignition means and having means responsive to the need for operation of the fuel burner, comprising: a transformer relay having two secondary windings and having a switch movable from an open to a. closed circuit condition upon an electrical circuit being completed through said transformer relay secondary windings, combustion responsive means including a bimetal arranged to be heated by the presence of flame at the fuel burner and including a movable member movable from a first to a second position upon said bimetal being subjected to a temperature rise, said movable member being movable from said second position to said first position upon said bimetal experiencing a subsequent temperature fall, a switch controlled by said combustion responsive means movable member and arranged to move from circuit open to circuit closed condition upon said movable member moving from said first to said second position, timing means including an electrically energizable actuator, a starting switch, latch means jointly controlled by said timing means and said combustion responsive means movable member and arranged to control said starting switch and to maintain said starting switch in closed circuit condition so long as said timer is in its initial position, said timer moving to a second position after a time period of energization of said timer actuator to thereby cause said starting switch to assume its open circuit condition, reset means controlled by said combustion responsive means movable member and arranged to reset said latch means and thereby reset said start switch to its circuit closing condition upon said movable member moving from said second to said first position in response to said combustion responsive bimetal experiencing a temperature fall indicative of the absence of flame at the fuel burner unit, an ignition switch controlled by said latch means and arranged to move from a circuit closed to a circuit open condition upon said timer moving from said initial to said second position, energizing circuit means for the secondary windings of said transformer relay including terminals adapted to be connnected to the means responsive to the need for operation of the fuel burner and including said starting switch and said timer actuator, further circuit means adapted to be connected to the fuel burner and including said relay switch and said ignition switch to energize the fuel burner under the control of said relay switch and to energize the ignition means under the control of said relay switch and said ignition switch, and running circuit means arranged to maintain one of the secondary windings of said transformer relay energized under the control of the means responsive to the need for operation of the fuel burner and including the switch of said combustion responsive means, said combustion responsive means switch completing a further circuit to temporarily maintain the actuator of said timer energized under the control of said start switch and said combustion responsive means switch.

5. Burner control apparatus for use with a fuel burner unit comprising: relay means including an actuator and a switch movable from an open to a closed condition upon energization of said relay actuator, a source of voltage having a first and a second portion; combustion responsive means including a movable member movable from a first to a second position upon said combustion responsive means being subjected to a flame at the fuel burner unit, said movable member moving from said second to said first position upon said combustion responsive means experiencing a subsequent absence of flame at the fuel burner unit, a first and a second switch controlled by said combustion responsive means, said first switch being in closed condition and moving to open condition upon said movable member moving from said first to said second position, said second switch being in open condition and moving to closed condition upon said movable member moving from said first to said second position; timing means including an electrical energizable actuator, a normally closed start switch, a movable latch member jointly controlled by said timing means and said combustion responsive means movable member and arranged to latch said start switch in the closed position and to allow said start switch to move to open position after a time period of energization of said timer actuator and to then latch said start switch in said open position independent of the state of energization of said timer actuator, means controlled by said combustion responsive means movable member arranged to reset said latch member and thereby cause said start switch to again assume said closed condition upon said combustion responsive means movable member moving from said second to said first position, initial energizing circuit means for the actuator of said relay including the first and second portions of said voltage source, said first combustion responsive means switch, said start switch, and said timer actuator connected in a series circuit; fuel burner unit energizing circuit means including terminals adapted to be connected to the fuel burner unit and controlled by said relay switch, and running circuit means for said relay actuator controlled by the second combustion responsive means switch and including said first portion of said voltage source,

References Cited in the file of this patent UNITED STATES PATENTS 2,185,317 Schmieding Jan. 2, 1940 2,212,255 Wallis et a1 Aug. 20, 1940 2,408,047 Cunningham Sept. 24, 1946 2,842,192 Penn July 8, 1958 

